The instance id for the characteristic for which this transition applies to (aka the ColorTemperature characteristic).
Defines the interval in milliseconds on how often the accessory may send even notifications to subscribed HomeKit controllers (aka call updateValue. Typically this is 600000 aka 600 seconds aka 10 minutes or 300000 aka 300 seconds aka 5 minutes.
It is not necessarily given, that we have the same time (or rather the correct time) as the HomeKit controller
who set up the transition schedule.
Thus we record the delta between our current time and the the time sent with the setup request.
timeMillisOffset is defined as
Date.now() - transitionStartMillis;.
So in the case were we actually have a correct local time, it most likely will be positive (due to network latency).
But of course it can also be negative.
Start of the transition in epoch time millis (as sent from the HomeKit controller). Additionally see timeMillisOffset.
Interval in milliseconds specifies how often the accessory should update the color temperature (internally). Typically this is 60000 aka 60 seconds aka 1 minute. Note notifyIntervalThreshold